Stakes are used in a variety of applications. For example, whenever concrete is poured for a foundation or a sidewalk, a form must be built to contain the liquid concrete and to shape it while it hardens. The form is little more than planks of wood horizontally fixed to the ground with stakes. The stakes are typically pieces of wood with a pointed end and a flat end. The stakes are pounded into the ground with a mallet or hammer. The form are then fixed to the stakes with appropriate fasteners such as nails or ties. After the concrete hardens, the forms are removed which requires pulling the stakes from the ground.
Removing the stake from the ground can be an arduous task. Attempting to remove the stake by hand can lead to severe physical injury to one's back. Moreover, the stake is rough on the hands. Some construction workers attempt to loosen the stake first by kicking it. Of course, this can easily lead to injury to the foot. Other workers might try to loosen the stake with a mallet. However, striking the stake can damage the concrete. A need exists for a mechanical device for removing the stake.
One example of such a device is disclosed in U.S. Pat. No. 2,777,726 to Lundgren et at. entitled "Post Removing Device." The Lundgren device uses a lever and fulcrum for mechanical advantage. A post engaging element is pivotally attached to the distal end of the lever. The post engaging element includes an L-shaped arm and a slidable jaw. The post is captured between the arm and jaw. The lever is then used to pull the stake upward. The post is captured by force exerted by both the arm and the slidable jaw. However, the arm and slidably jaw necessarily apply these forces at different points on opposite sides of the post. Thus, the Lundgren device produces shear and bending forces on the post. This may be of little concern with metal posts, but can be ruinous when applied to old wooden stakes used in construction.
Another example of a stake puller is disclosed in U.S. Pat. No. 4,161,310 to Parker entitled "Metal Fence Post Puller." The Parker device also uses a lever and fulcrum to gain mechanical advantage. A pair of flat bar members are pivotally attached to one end of the lever arm. A connecting member extends between the bar members. A pair of semidisc members are rigidly fixed to the end of the lever arm. The puller is positioned so the post is captured between the bar members, the semidisc plates and the connecting member. When the lever arm is pivoted about the fulcrum, the post is pinched between the semidisc plates and the connecting member. However, as with the Lundgren device described above, the forces applied by the semidisc plates and the connecting member are not directly opposite to each other, resulting in a bending force to the post. Of course, Parker only envisions the use of his post puller with metal fence posts.
A need exists for a stake puller suitable for use with wooden stakes. Such a stake puller must minimize any bending forces applied to the stake. Such a puller must also be effective in removing stakes driven deeply into the ground. Specifically, the puller should be capable of being "pumped," or reapplied to the stake without having to reposition the puller between each effort.